A conventional photomultiplier tube includes a photocathode provided on an end of a vacuum vessel for emitting electrons, an electrode-layered unit disposed in opposition to the photocathode and configured of layered electrodes including a plurality of dynodes for multiplying the emitted electrons, and a plurality of anodes for detecting the multiplied electrons (for example, refer to patent documents 1 through 3). In such a photomultiplier tube, connecting pieces formed on peripheral sections of each electrode constituting the electrode-layered unit are electrically connected to stem pins fixed to a stem constituting the other end of the vacuum vessel. As a result, an effective area of each electrode is configured to be within a region surrounded by the stem pins arranged on the peripheral sections of each electrode. Further, another known photomultiplier tube is configured so that connecting sections with the stem pins protrude to the effective areas of dynodes or anodes (for example, refer to patent document 4).
Patent document 1: Japanese Patent Application0 Publication No. H9-288992 (page 4, FIG. 2)
Patent document 2: Japanese Patent Application Publication No. 2000-149860 (page 3, FIG. 1)
Patent document 3: International Application Publication No. WO2003/098658 (pages 14, FIG. 5(A))
Patent document 4: Japanese Patent Application Publication No. S59-221957 (page 3, FIG. 5)